全文获取类型
收费全文 | 331篇 |
免费 | 50篇 |
国内免费 | 53篇 |
专业分类
测绘学 | 14篇 |
大气科学 | 20篇 |
地球物理 | 42篇 |
地质学 | 156篇 |
海洋学 | 16篇 |
天文学 | 162篇 |
综合类 | 12篇 |
自然地理 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 13篇 |
2012年 | 30篇 |
2011年 | 10篇 |
2010年 | 30篇 |
2009年 | 11篇 |
2008年 | 42篇 |
2007年 | 12篇 |
2006年 | 41篇 |
2005年 | 20篇 |
2004年 | 7篇 |
2003年 | 25篇 |
2002年 | 28篇 |
2001年 | 22篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 18篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有434条查询结果,搜索用时 31 毫秒
411.
A cloud point extraction procedure is presented for the preconcentration and simultaneous determination of Ag+ and Pd2+ in various samples. After complexation with 2‐((2‐((1H‐benzo[d]imidazole‐2‐yl)methoxy)phenoxy)methyl)‐1H‐benzo[d]imidazol (BIMPI), which was used as a new chelating agent, analyte ions were quantitatively extracted to a phase rich in Triton X‐114 following centrifugation, and determination was carried out by flame atomic absorption spectrometry (FAAS). Under the optimum experimental conditions (i. e., pH = 7.0, 15.0·10–5 mol/L BIMPI and 0.036% (w/v) Triton X‐114), calibration graphs were linear in the range of 28.0–430.0 μg/L and 57.0–720.0 μg/L with detection limits of 10.0 and 25.0 μg/L for Ag+ and Pd2+, respectively. The enrichment factors were 35.0 and 28.0 for Ag+ and Pd2+, respectively. The method has been successfully applied to evaluate these metals in some real samples, including waste water, soil and hydrogenation catalyst samples. 相似文献
412.
413.
P-T-X (CO2 ) conditions in mafic and calc-silicate hornfelses from Oberon, New South Wales, Australia
A. S. ANDREW 《Journal of Metamorphic Geology》1984,2(2):143-163
Abstract The Rockley Volcanics from near Oberon, New South Wales occur within the aureole of the Carboniferous Bathurst Batholith and have been contact metamorphosed at P ∼ 100 ± 50MPa (10.5kbar) and a maximum T ∼ 565°C in the presence of a C–O–H fluid. Prior to contact metamorphism the volcanics were regionally metamorphosed and altered with the extensive development of actinolite, chlorite, plagioclase, quartz and calcite. The contact metamorphosed equivalents of these rocks have been subdivided into: Ca-poor (cordierite + gedrite), Mg-rich (amphibole + olivine + spinel), mafic (amphibole + plagioclase) and Ca-rich (amphibole + garnet + diopside; diopside + plagioclase; garnet + diopside + wollastonite) rocks.
The chemistry of the minerals in the hornfelses was controlled by the bulk rock chemistry and fluid composition. Pargasites and hastingsites as well as an unusual phlogopite with blue green pleochroism, are found in Ca-rich hornfelses. A comparison of the assemblages with experimentally derived equilibria suggests that the fluid phase associated with the Ca-rich hornfelses was water-rich (Xco2 = 0.1 to 0.3) while that associated with the Mg-rich hornfelses was enriched in CO2 (Xco2 > 0.7). The different hornfels types have reacted to contact metamorphism independently in both their solid and fluid chemistries. 相似文献
The chemistry of the minerals in the hornfelses was controlled by the bulk rock chemistry and fluid composition. Pargasites and hastingsites as well as an unusual phlogopite with blue green pleochroism, are found in Ca-rich hornfelses. A comparison of the assemblages with experimentally derived equilibria suggests that the fluid phase associated with the Ca-rich hornfelses was water-rich (X
414.
中国岩石圈三维结构数据库数据可视化控件的设计与实现 总被引:1,自引:1,他引:1
中国岩石圈三维结构数据库和其他研究场合涉及大量数据可视化问题。研制数据可视化控件可以达到最大程度的重用,各种二维数据可视化控件用Visual Basic开发,用Windows API提高图形绘制能力。开发中从控件的显示界面、控件的属性、控件的事件和方法等方面进行规划和实现。对于各种地球物理数据可视化,除了涉及数据的控件专业属性、数据的传递和图形的具体绘制过程不同外,控件的其他部分是相同的,因此在开发不同的控件时可以重用大部分的代码和设计思想。 相似文献
415.
X荧光分析方法在地球化学勘查中的应用--四川理塘铜、锡、铅、银异常查证 总被引:1,自引:3,他引:1
介绍了X荧光技术在四川理塘颇昂佐避地区地球化学普查中的应用。工作现场利用X荧光测量水系沉积物样品的异常区,反映了含矿岩性矿(化)体的大致概况。利用该技术圈定的异常,经探槽揭露证实为矿化异常。实践证明,在四川西部交通、生活极为困难的高寒山区,X荧光技术是一种快速、经济、有效的地球化学普查方法。 相似文献
416.
中朝地台内部无争议的志留系只有朝鲜半岛平南盆地的谷山组和宝良里组。中朝地台北缘活动陆缘带志留系比较发育,有桃山组、西别河组(至少其大部分)等。李河荣等根据牙形刺将朝鲜半岛太白山盆地的桧洞里组划归志留系,但是从层序、岩石和安太庠修定的牙形刺化石来看,桧洞里组可能不是志留系,而是与中朝地台华北区峰峰组八陡段(或包括部分耀县组)可比的中奥陶世地层。微体古生物学家安太庠和李河荣分别为中国和韩国的牙形学及其生物地层学研究做出了重要贡献。他们的英年早逝,对东北亚地学研究是一个重大损失。 相似文献
417.
418.
便携式波长色散X射线荧光光谱仪及初步应用 总被引:4,自引:1,他引:3
介绍了SPECTROSCAN-U便携式波长色散X射线荧光光谱仪的技术指标及特点;使用该仪器并采用粉末样品压片制样测定了水系沉积物及土壤样品中的11个元素,得到了较好的精密度和准确度,为野外现场测试作了有益的尝试。 相似文献
419.
L. Paul Bédard 《Geostandards and Geoanalytical Research》2008,32(4):399-403
These mature analytical techniques do not show any change in publication level from the previous two years and AAS remains dominant in terms of the number of publications. The last two years have seen fewer technical improvements than in the previous review period. Some interesting papers dealing with uncertainty and quality assurance in INAA were published during 2006–2007. It is suggested that photon activation should be reconsidered because the source of electron accelerators has recently improved. A technique to preconcentrate Se for INAA determination has also been proposed. In the case of AAS, papers on analyte preconcentration continue to be more abundant than those relating to instrumental modification. Sample preparation for AAS is also active and ultrasound‐assisted leaching shows some promising applications. There were an unusual number of reviews concerned with AAS and those important to geological samples are cited here. A technique to preconcentrate Cr in water is presented and a new device to determine As and Se is showing some potential uses. Confocal X‐ray mapping continues to show interesting developments. One group developed a technique to perform XRF inside an oyster and an interesting application of μ‐XRF mapping of sediments is presented. Determination of platinum‐group elements (at μg g1 concentrations) can be carried out very quickly with an improved XRF technique. 相似文献
420.
布尔代数是计算机进行逻辑运算的基础,它为自动化制图提供了理论基础和数学工具。本文根据论域的幂集P(X)为布尔代数且其偏序关系为包含关系的数学原理,通过改变论域而分别对地图图像系统、地图符号系统和地图数据库系统等多种地图符号系统的布尔代数结构,分别作出了有别于应用布尔代数定义和定理的简要证明。文章给出了以点的特征变换构建地图符号、地图注记和实现面状域色彩变换的实例,阐释了地图图像系统中的布尔运算;还给出了通过基础图层上地图符号的增删,构建不同图层和不同图层叠合构建不同类型地图的实例,说明以点集形式为基本元素的地图符号系统和地图数据库系统也适于布尔运算。 相似文献